72 Distinguishing features of MIS-C to other paediatric febrile diseases in the acute setting

Abstract Background Multisystem inflammatory syndrome in children (MIS-C) presents with fever, shock, rash, abdominal pain and raised inflammatory markers, as well as common features of inflammatory childhood illnesses. In the acute setting, especially in countries where infectious diseases are common differential diagnoses, it is challenging to diagnose MIS-C. Therefore, data differentiating MIS-C from other inflammatory and/or febrile diseases at presentation is needed. Methods Prospective data was collected from children admitted to the Red Cross War Memorial Children’s Hospital in Cape Town, South Africa from May 2020 to end November 2021 where MIS-C was part of their differential diagnoses. Clinical features on the day of admission were compared between children with confirmed MIS-C (MIS-C+) and those with alternate diagnoses (MIS-C-). Results In this time period, 60 children were MIS-C+ and 34 were MIS-C-. There was no significant difference in age (p = 0.321), sex (p = 0.525), ethnicity (p = 0.279), or in the frequency of comorbidities (p = 0.151) between the two groups. The presence of conjunctivitis (OR = 8.12), rash (OR = 8.67), tachycardia (OR = 2.8) and oral mucositis (OR = 3.75) was associated with MIS-C+ while abdominal pain and hypotension were not. MIS-C+ had statistically higher median C-reactive protein (CRP), pro-brain natriuretic protein (pro-BNP) and ferritin, and lower median lymphocyte count, platelet count and sodium levels than MIS-C-. Ferritin discriminated MIS-C+ well (AUC = 0.86) with a 94% sensitivity and 60% specificity at a cut off of > 195ng/l. Sodium had an AUC of 0.72, with a 70% sensitivity and 71% specificity at a cut off of < 132.5 mmol/l. CRP did not distinguish MIS-C well (AUC = 0.52) and although they had good AUC, platelet count and pro-BNP had cut off values in the normal range decreasing clinical utility. Conclusion We provide evidence for the use of accessible clinical and laboratory variables for the diagnosis of MIS-C in diverse settings. Implications These data will aid clinicians to do a rapid diagnosis (and ultimately treat earlier) of patients with MIS-C in the acute setting, especially those in under-resourced settings. 72 Table 4 ROC analysis of laboratory tests which were different between MIS-C- and MIS-C+ Test AUC (95%CI) p Potential cut-off value Sensitivity Specificity Youden ratio Ferritin 0.86 (0.70, 1) 0.017 *>195 94% 60% 54% 7-84 ng/L ** >316 72% 80% 52% Pro-BNP 0.80 (0.62, 0.98) 0.044 *>239 83% 40% 23% <450 ng/L ** >378 78% 80% 57% Platelet count 0.75 (0.59, 0.90) 0.006 *<285 81% 71% 52% 180-440 x109/L Sodium 0.726 (0.56, 0.88) 0.014 *<134.5 87% 35.7% 22% 136-145 mmol/L ** <132.5 70% 71% 41% CRP 0.54 (0.62, 0.98) 0.766 *>77 100% 40% 40% <10 mg/L ** >161.5 50% 60% 10% 2 potentials cut off values are given.* the value which gives the best specificity with a sensitivity >80% and.** the value that achieves the best sensitivity with a specificity of at least 60%.


Background
Multisystem inflammatory syndrome in children (MIS-C) presents with fever, shock, rash, abdominal pain and raised inflammatory markers, as well as common features of inflammatory childhood illnesses. In the acute setting, especially in countries where infectious diseases are common differential diagnoses, it is challenging to diagnose MIS-C. Therefore, data differentiating MIS-C from other inflammatory and/or febrile diseases at presentation is needed. Methods Prospective data was collected from children admitted to the Red Cross War Memorial Children's Hospital in Cape Town, South Africa from May 2020 to end November 2021 where MIS-C was part of their differential diagnoses. Clinical features on the day of admission were compared between children with confirmed MIS-C (MIS-Cþ) and those with alternate diagnoses (MIS-C-).

Results
In this time period, 60 children were MIS-Cþ and 34 were MIS-C-. There was no significant difference in age (p ¼ 0.321), sex (p ¼ 0.525), ethnicity (p ¼ 0.279), or in the frequency of comorbidities (p ¼ 0.151) between the two groups. The presence of conjunctivitis (OR ¼ 8.12), rash (OR ¼ 8.67), tachycardia (OR ¼ 2.8) and oral mucositis (OR ¼ 3.75) was associated with MIS-Cþ while abdominal pain and hypotension were not. MIS-Cþ had statistically higher median C-reactive protein (CRP), pro-brain natriuretic protein (pro-BNP) and ferritin, and lower median lymphocyte count, platelet count and sodium levels than MIS-C-. Ferritin discriminated MIS-Cþ well (AUC ¼ 0.86) with a 94% sensitivity and 60% specificity at a cut off of > 195ng/l. Sodium had an AUC of 0.72, with a 70% sensitivity and 71% specificity at a cut off of < 132.5 mmol/l. CRP did not distinguish MIS-C well (AUC ¼ 0.52) and although they had good AUC, platelet count and pro-BNP had cut off values in the normal range decreasing clinical utility.

Conclusion
We provide evidence for the use of accessible clinical and laboratory variables for the diagnosis of MIS-C in diverse settings.

Implications
These data will aid clinicians to do a rapid diagnosis (and ultimately treat earlier) of patients with MIS-C in the acute setting, especially those in under-resourced settings. 72  Background Primary dysautonomia is a disorder of the autonomic nervous system with nonspecific manifestations, mainly affecting blood pressure and heart rate.

Objective
We report the diagnostic odyssey in an 11-year-old girl starting with arthralgia and leading to the final diagnosis of a rare dysautonomia.

Methods
A 13-year-old girl, with no pathologic history, was admitted to pediatrics for diffuse arthralgia without clinical inflammatory signs. Biological exploration unmasked a morning proteinuria without hypoalbuminemia and with a normal electrophoretic profile, microcytic anaemia and orthostatic hypotension authenticated during his hospitalization. Exhaustive explorations were undertaken (including autoimmune panel, ophthalomological examination, full metabolic screen and even renal biopsy), without any conclusive result.

Results
The development-after one year of follow up-of arterial hypertension, associated with orthostatic hypotension and proteinuria, points toward the extremely rare defect in baroreceptors. The management, in collaboration with the cardiology department, enhanced the patient's quality of life with a reduction in hypertensive peaks. An appropriate lifestyle also amended the intensity of orthostatic hypotension. The close multidisciplinary follow-up over >48 months is reassuring.

Conclusion
The peculiar baroreceptor defect in a context of dysautonomia should be kept in mind in the (long) list of differential diagnosis of arthralgias, as joint pain can be triggered by dysautonomia. Management is mainly symptomatic.